//You are given an array of integers nums, there is a sliding window of size k 
//which is moving from the very left of the array to the very right. You can only 
//see the k numbers in the window. Each time the sliding window moves right by one 
//position. 
//
// Return the max sliding window. 
//
// 
// Example 1: 
//
// 
//Input: nums = [1,3,-1,-3,5,3,6,7], k = 3
//Output: [3,3,5,5,6,7]
//Explanation: 
//Window position                Max
//---------------               -----
//[1  3  -1] -3  5  3  6  7       3
// 1 [3  -1  -3] 5  3  6  7       3
// 1  3 [-1  -3  5] 3  6  7       5
// 1  3  -1 [-3  5  3] 6  7       5
// 1  3  -1  -3 [5  3  6] 7       6
// 1  3  -1  -3  5 [3  6  7]      7
// 
//
// Example 2: 
//
// 
//Input: nums = [1], k = 1
//Output: [1]
// 
//
// Example 3: 
//
// 
//Input: nums = [1,-1], k = 1
//Output: [1,-1]
// 
//
// Example 4: 
//
// 
//Input: nums = [9,11], k = 2
//Output: [11]
// 
//
// Example 5: 
//
// 
//Input: nums = [4,-2], k = 2
//Output: [4]
// 
//
// 
// Constraints: 
//
// 
// 1 <= nums.length <= 10⁵ 
// -10⁴ <= nums[i] <= 10⁴ 
// 1 <= k <= nums.length 
// 
// Related Topics Array Queue Sliding Window Heap (Priority Queue) Monotonic 
//Queue 👍 7580 👎 274


package leetcode.editor.en;

import java.util.LinkedList;

public class _239_SlidingWindowMaximum {
    public static void main(String[] args) {
        Solution solution = new _239_SlidingWindowMaximum().new Solution();
        int[] ints = solution.maxSlidingWindow(new int[]{1, 3, -1, -3, 5, 3, 6, 7}, 3);
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class Solution {
        public int[] maxSlidingWindow(int[] nums, int k) {
            if (nums == null || nums.length<2) {
                return nums;
            }
            int[] result = new int[nums.length-k+1];
            LinkedList<Integer> queue = new LinkedList<>();
            for (int i = 0; i < nums.length; i++) {
                while (!queue.isEmpty() && nums[queue.peekLast()]<=nums[i]) {
                    queue.pollLast();
                }
                queue.addLast(i);
                if (queue.peek()<=i-k){
                    queue.poll();
                }
                if (i+1>=k) {
                    result[i+1-k] = nums[queue.peek()];
                }
            }
            return result;
        }
        public int[] maxSlidingWindow1(int[] nums, int k) {
            if(nums == null || nums.length < 2) return nums;
            // 双向队列 保存当前窗口最大值的数组位置 保证队列中数组位置的数值按从大到小排序
            LinkedList<Integer> queue = new LinkedList();
            // 结果数组
            int[] result = new int[nums.length-k+1];
            // 遍历nums数组
            for(int i = 0;i < nums.length;i++){
                // 保证从大到小 如果前面数小则需要依次弹出，直至满足要求
                while(!queue.isEmpty() && nums[queue.peekLast()] <= nums[i]){
                    queue.pollLast();
                }
                // 添加当前值对应的数组下标
                queue.addLast(i);
                // 判断当前队列中队首的值是否有效
                if(queue.peek() <= i-k){
                    queue.poll();
                }
                // 当窗口长度为k时 保存当前窗口中最大值
                if(i+1 >= k){
                    result[i+1-k] = nums[queue.peek()];
                }
            }
            return result;
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}